Knee injuries are common and are painful events for recreational and elite sportspersons. A well-documented risk factor for knee injuries is the degree of change in angular alignment occurring at the knee joint during a dynamic activity. The change in angular alignment is commonly referred to as valgus or varus depending on whether the knee angles inward (valgus) or outwards (varus). In anatomical terms, alignment of the tibial tubercle with the pelvis is also referred to as Q-angle. The change in angular alignment of the knee describes the knee moving medially whilst the foot is fixed to the ground (valgus) or the knee moving laterally whilst the foot is fixed to the ground (varus), increasing the angle between the femur and the tibia. When movement causing change in angular alignment of the knee occurs, it may be in combination with flexion of the knee known as tibio-femoral flexion, internal rotation of the femur, pronation of the foot and/or relative flexion of the hip joint.
Alignment of the knee, hip and ankle as a person squats, jumps, hops, walks or runs has been a regular test or assessment carried out by therapists when assessing an athlete or sportsperson. The therapist may subjectively (visually) rate whether the athlete/sportsperson performed the test well or poorly using a rating system such as 1 (good), 2 (average) or 3 (poor).
Although the rating system may provide a subjective impression of valgus or varus movement when squatting or landing from a hop/jump, the test is currently not measured objectively and instead is subjectively assessed based on visual observations. Video techniques may be used to visualise alignment of the femur with the tibia, while software packages may allow a user to align traces on a screen with angular motion of different limbs of the body to estimate the valgus/varus angle. Optical tracking markers may also be used with high frame rate cameras to capture this type of movement in a laboratory setting. However, these procedures are time consuming to post analyse, often have visual occlusions due to limb movement, do not provide real time data and typically need to be captured in a controlled environment with access to specialist equipment and staff.
The method and apparatus of the present invention may at least alleviate the disadvantages of the prior art. The present invention may also provide real time feedback, while not requiring video analysis, to allow an athlete/player to adjust their movement patterns in real time, based on the real time feedback.
A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was known or that the information it contains was part of the common general knowledge in Australia or elsewhere as at the priority date of any of the disclosure or claims herein. Such discussion of prior art in this specification is included to explain the context of the present invention in terms of the inventor's knowledge and experience.
Throughout the description and claims of this specification the words “comprise” or “include” and variations of those words, such as “comprises”, “includes” and “comprising” or “including, are not intended to exclude other additives, components, integers or steps.